Is there any functionality built into the theme to do a gallery with pop-up, similar to this? https://huge-it.com/wordpress-plugins-gallery-demo/#plugin_demo_wrapper
Yes you can also use it with blog posts. You have to edit blog posts in visual page builder mode to use it which has some restrictions.
If you don’t want to use it then you can use Jetpack plugin and the gallery provided by it https://jetpack.com/support/tiled-galleries/